A construction method gaining wide acceptance today involves the construction of a form from modular hollow plastic units which then are filled with concrete. The concrete is allowed to set with the plastic form remaining in place. A number of approaches of this method have been described previously.
U S. Pat. No. 3,383,817 to Gregori discloses a form structure for concrete having two side-by-side composite panel members and a plurality of tension members interconnecting the panel members.
U.S. Pat. No. 3,552,076 to Gregori discloses a self-supporting concrete form of foamed polymeric material having end and side walls and at least one partition between the side walls with projections and recesses on the upper and lower edges of the side walls for interlocking several of the forms.
U.S. Pat. No. 3,788,020 to Gregori discloses a self-supporting concrete form of foamed polymeric material in which two side walls are joined by a transverse sheet metal tension member. The side walls have a tongue and groove arrangement on the upper and lower surfaces and end portions for interlocking several of the forms.
U.S. Pat. No. 4,223,501 to DeLozier discloses a one piece transverse connecting member having a plurality of openings for self-supporting concrete forms of the type disclosed in U.S. Pat. No. 3,778,020.
U.S. Pat. No. 4,439,967 to Dielenberg discloses a plastic formwork for concrete having a complex interlocking configuration on the upper and lower edges of the side and end walls.
U.S. Pat. No. 4,516,372 to Grutsch discloses a concrete form having a plurality of panels with shiplap joint edges which are held in place by metal ties,
U.S. Pat. No. 4,577,447 to Doran discloses a plastic building block form constructed from two parts adhesively bound together and presenting a series of horizontally and vertically aligned openings to accommodate the flow of concrete.
U.S. Pat. No. 4,604,843 to Ott discloses concrete forms having horizontal base elements, horizontal connecting elements, and ladder-like vertical elements bridging the slabs of the form.
U.S. Pat. No. 4,698,947 to McKay discloses an insulated wall of spaced-apart foamed plastic sheets (between which concrete is poured) with a plurality of sheet metal ties holding the sheets together.
U.S. Pat. No. 4,706,429 and U.S. Pat. No. 4,730,422 to Young disclose a plastic wall tie for modular foamed plastic concrete forms having a pair of triangular truss sections and T-shaped end sections.
U.S. Pat. No. 4,731,968 to Obino discloses a concrete formwork having two panel members, each having a plurality of plugs on its upper side and corresponding recesses in its lower side, together with associated cross members.
U.S. Pat. No. 4,742,659 to Meilleur discloses a formwork for concrete having two separate foam modules and a combination of tie and coupling rods.
U.S. Pat. No. 4,750,308 to McKay discloses tie members for spaced apart plastic sheets having a pair of metal plates joined by twisted metal strips.
U.K Patent Specification No. 985,914 to Hinse discloses hollow artificial stones or blocks having complementary tongue and grooves on the top and bottom faces which are stacked in interlocking relationship and filled with concrete.
U.K Patent Specification No. 1,385,045 to Ito discloses a partition element of two parallel rectangular plates linked together with bridge members.
French Patent No. 2,394,647 discloses plastic forms for concrete having complementary mortise and tenon joints.